Light shield for an indicating instrument

ABSTRACT

A light shield for an indicating instrument including a face plate having a forward surface in view of the user and a rearward surface adjacent a lighted indicating element, the plate having an elongated window therein for viewing the indicating element, the elongated window having a cross-sectional configuration providing a first, flat portion substantially normal to the face plate and extending rearwardly thereof and the window having a second, arcuate portion extending from the rearward surface of the plate from one edge of the window, the arcuate portion intersecting the rearward end of the flat portion, the arcuate portion being transparent and all other portions of the plate being opaque.

Elite- 1 Barrett et al.

States Patent LIGHT SHIELD FOR AN INDICATING OTHER PUBLICATIQNSINSTRUMENT ,7 V 1 V t a .o t it Pub]. Heath Klt Flsh Spotter". Heath Co.Ma1l Order Inventors: Burton M. Barrett; Bllyrl A. No. (P g Franks, bothof Tulsa, Okla.

[73] Assignee: Lawrance Electronics Mfg. C0rp., Primary Examiner-RichardC. Queisser Tulsa, Okla. Assistant ExaminerDaniel M. Yaslch [22] Filed:Nov 8, 1971 Attorney-Head & Johnson [21] Appl. No.: 196,608 [57]ABSTRACT A light shield for an indicating instrument including a 2 g 2323??? face plate having a forward surface in view of the user i 3 1'324/156 and a rearward surface adjacent a. lighted indicating el- 1 e 241 4 l 46 ement, the plate having an elongated window therein 6 3 E 8 5for viewing the indicating element, the elongated window having across-sectional configuration providing a first, flat portionsubstantially normal to the face plate [56] References C'ted andextending rearwardly thereof and the window hav- UNITED STATES PATENTSing a second, arcuate portion extending from the rear- 3,488,102 1/1970Webb 350/276 SL ward surface of the plate from one edge of the window,2,941, 41 6/ 60 St gi 324/156 X the arcuate portion intersecting therearward end of the D f-i flat portion, the arcuate portion beingtransparent and o 3,214,596 10/1965 Schwerdt, Jr. et al. 350/276 R allpom) the plate bemg opaque Bradley X 6 Claims 3 Drawing Figures2,863,039 12/1958 Ruschell 240/4653 X 3 0 l4 3 /6A l8 t; M 32RBACKGROUND, SUMMARY AND OBJECTS OF THE INVENTION This invention isdirected towards an apparatus in which a lighted indicating element ispositioned behind a plate having a window and is intended to providemeans wherein the lighted indicating element is better visibly observedwhen the instrument is used in high ambient light. As one specificexample, the invention is particularly related to a rotating disk typedepth and fish indicating apparatus. Such apparatus is sued both in dayand night fishing and consequently is frequently used in bright outdoorlight. A popular type of depth and fish indicating apparatus is thatwhich uses a rotated disk on which is mounted a neon bulb. The diskrotates in synchronization with the transmission of sound pulses in thewater and the neon bulb flashes light in response to amplified signalstriggered by echoes received by a transponder positioned in the water.In order to protect the rotating disk and neon bulb it is customary toposition them behind a plate having a window therein, the window beingin circular form. In some instruments the windows are open so thatnothing exists to obstruct the passage of the light from the rotatingneon bulb through the window to the user. From an optical standpointsuch arrangement is very good, but it has other defects. With an openwindow nothing exists to protect the rotating disk and the bulb fromencountering a physical object stuck through the window. The rotatingdisk and bulb cause distracting noise which freely passes through theopen window. in addition, the open window permits dust and water toenter the interior of the instrument. To overcome these problems somemanufacturers close the window with glass. While a sheet of glass orclear plastic provides physical protection for the equipment, reducesnoise, and'keeps out dust and water, an additional problem isintroduced. Sunlight striking the glass or plastic is reflected backinto the eyes of the viewer and substantially decreases the ability ofthe viewer to observe light from the bulb rotating behind the window.Thus, the use of a flat plate of glass or plastic reduces the opticalcharacteristics of the instrument and makes it more difficult to use inbright light.

This invention provides a light shield for an indicating instrument,such as of the type described, which has the advantages above enumeratedfor a transparent window for such instruments, but in addition includesimproved means of transmitting light from the indicating instrumentthrough to the user while at the same time reducing reflection fromambient light.

It is therefore an object of this invention to provide a light shieldfor an indicating instrument.

More particularly, an object of this invention is to provide a lightshield for an indicating instrument of the type having a lightedindicating element behind a window, including improved means ofpermitting light from the indicating instrument to pass through to theuser but reducing the amount of relfeetion from ambient light, such assunlight.

These general objects, as well mother and more specit'ic objects, willbe fulfilled in the following description and claims. taken inconjunction with the attached drawing.

DESCRIPTION OF THE VIEWS FIG. 1 is a front view of an instrumentincorporating this invention. The instrument illustrated is the typeused for indicating depth and the presence of fish in water and isexemplary of one type of instrument to which this invention may beapplied.

FIG. 2 is a cross-sectional view taken along the line 2-2 of FIG. 1showing the instrument in cross-section.

FIG. 3 is an enlarged cross-sectional view of the window portion of thelight shield of this invention.

DETAILED DESCRIPTION Referring now to the drawings, and rist to FIG. 1,an example of one application of the invention is illustrated. A depthand fish indicating; insturment is generally dientified by numeral 10,the instrument shown being mounted on a gimbal type bracket 12. Theinstrument 10 includes a face plate 14 having an opening 16 therein. Theopening 16 is shown in four segments. The opening 16 has a first edge16A and a second, smaller diameter edge 163.

As shown in FIG. 2, the fac plate 14 has a forward surface 14A towardthe viewer and a rearward surface 148 opposite the viewer. Positionedbehind the face plate 14 is a rotating disk 18 having a neon bulbmounted thereon. Disk 18 is rotated by shaft 22 extending from a motor24. A slip ring 26 affixed to disk 18 is connected electrically to bulb20 by conductor 28. A brush 30 contacts slip ring 26. The brush isconnected to electronic equipment (not shown) by which electrical energyis applied to the :slip ring and thus to bulb 20 to cause it to ignite.When the instrument is a depth and fish indicating device, bulb 20ignites in response to reflected echoes from a transponder (not shown)and thus the rotational position of disk 18 is an indication of thedepth of the object producing the echo.

The instrument described to this point .is not unlike others well knownin the industry. As previously indicated opening 16 may be completelyleft open to fully expose bulb 20 to the viewer, however, such has thedisadvantages above-mentioned. Others have used a flat plate of clearplastic or glass to close opening 16, but this produces glare. Thisinvention is directed towards an optical arrangement for opening 16 topermit light from bulb 20 to fully pass therethrough to the user andwhich simultaneously reduces glare of bright light, such as sunlight.

Positioned against front plate rearward surface 148 is a window plate 32which may be of glass or clear plastic. At opening 16 the window plate32 includes, in cross-sectional configuration. a first portion 34 whichis flat and substantially normal to plate 32 and extends rearwardlythereof, the first portion having a forward end 34A which is coincidentwith opening edge 16A. The window plate 32 is further configured, incrosssection, by a second portion 36 which is arcuate and extends fromthe rearward surface of the window plate 32. Edge 36A of arcuate portion36 is thus coincident with edge 16A of the opening. The other edge 36Bof the arcuate portion intersects the rearward edge 34B of the windowfirst portion 34. A flange 38 supports the window plate 32 against therearward surface of the face plate 14.

The window plate first portion 34 is opaque, or at least the surface 34Cthereof facing arcuate portion 36 is opaque. This may be accomplishedsuch as by painting surface 34Cwith dark paint.

It can be seen that light from bulb 32 may freely pass through thetransparent arcuate portion 36 to the viewer. Ambient light, such assunlight, passing through opening 16, encounters the arcuate surface ofwindow second portion 36 and is reflected downwardly against surface 34Cwhich, being opaque, absorbs rather than reflects the light raysstriking it. In this way, much of the ambient light striking the opening16 is prevented from being reflected back to the eyes of the viewerwhile at the same time light from bulb 20 is permitted to pass freely.

FIG. 3 shows an alternate embodiment of the invention. As previouslyindicated, the window first portion 34 must be opaque (or at leastsurface 34C must be opaque). In the best arrangement the window plate 32is an integral piece so that the window first portion 34 and the secondportion 36 are formed of the same material. Since the window secondportion 36 must be transparent, it is difficult and expensive tomanufacture the plate wherein opaque and transparent portions arecontiguous and integral to each other. To overcome this problem anopaque cylinder 40 is positioned over the window first portion 34. Sincecylinder 40 is a separate item it can easily be manufactured of opaqueplastic or metal. Thus the entire window plate 32 may be of clearmaterial, such as clear plastic. Opaque cylinder 40 absorbs the lightreflected from the arcuate portion 36. Dotted line 42 illustrates thedirection ambient light, such as sunlight takes, in striking arcuateportion 36. It is reflected to opaque surface 34C, or the opaquecylinder 40, and is absorbed.

In the illustrated arrangement of the invention face plate 14 and windowplate 32 are shown as separate items. It can be seen that in thesimplest embodiment only a window plate 32 is required and all portionsof the window plate as described will be opaque except the windowarcuate portion 36 which must be transparent.

The invention has been described as it particularly relates to a type ofinstrument having a rotating disk, but the principles of the inventionare adaptable to any type of instrument utilizing a light indicatingelement. Opening 16 may be linear or any other configuration, rathr thancircular as shown.

While the invention has been described with a certain degree ofparticularity it is manifest that many changes may be made in thedetails of construction and in the arrangement of the components withoutdeparting from the spirit'and scope of this disclosure. it is understoodthat the invention is not limited to the embodiment illustrated hereinfor purposes of exemplification, but is to be limited only by the scopeof the attached claim or claims. including the full range of equivalencyto which each element thereof is entitled.

What is claimed:

1. A light shield for a casing of an indicating instrument comprising:

a face plate in said casing having a forward surface with indiciathereon and in view of the user and a rearward surface adjacent acondition responsive lighted indicating element, the face plateincluding an elongated integral window means for viewing the lightedindicating element, the 'elongated window means having first and secondspaced apart edges, said wondow means comprising in crosssectionalconfiguration:

a first portion substantially normal to the face plate and extendingrearwardly thereof, the first portion having a forward end and arearward end, the forward end being coincident with said first edge ofsaid window; and a a second portion arcuately extending from therearward surface of said face plate and from said second edge of saidelongated window and interconnecting with the rearward end of said firstwindow portion, the arcuate second window portion being transparent andthe other portions of the plate being opaque said arcuate second portionfreely passing light rays outwardly from said indicating element whilesimultaneously reflecting a substantial amount of ambient incoming lightrays into opaque portions of the plate.

2. A light shield according to claim 1 wherein said elongated windowmeans in said face plate is circular, said first edge being of a largerdiameter than the diameter of said second edge, said wondow firstportion forming a cylinder and said window second portion forming asubstantially truncated hemispheroid.

3. A light shield according to claim 2 including an opaque cylinderselectively forming a portion of said window first portion.

4. A light shield for an indicating instrument comprismg:

a forward opaque face plate in view of the user having an elongatedopening for viewing a condition responsive lighted indicating elementtherethrough, the elongated opening having first and second edges;

a window member rearwardly. of said opening in said plate, said windowmember comprising, in crosssectional configuration:

a first portion substantially normal to the face plate,

the first portion having a forward end and a rearward end, the forwardend being coincident with said first edge of said face plate opening,said first portion extending rearwardly of said face plate; and secondintegral arcuate portion extending from a rearward surface of said faceplate at said second edge of said window first portion, the firstportion of the window member being light absorbing and the secondportion being transparent said arcuate second portion freely passinglight rays outwardly from said indicating element while simultaneouslyreflecting a substantial amount of ambient incoming light rays intoopaque portions of the plate.

5. A light shield according to claim 4 wherein said elongated opening insaid face plate is circular, said first edge of said opening in saidface plate being of a diameter larger than the diameter of said secondedge, said window member first portion forming a cylinder and saidwindow member second portion forming a substantially truncatedhemispheroid.

6. A light shield according to claim 5 including an opaque cylinderselectively forming a portion of said window member first portion.

t t l l

1. A light shield for a casing of an indicating instrument comprising: aface plate in said casing having a forward surface with indicia thereonand in view of the user and a rearward surface adjacent a conditionresponsive lighted indicating element, the face plate including anelongated integral window means for viewing the lighted indicatingelement, the elongated window means having first and second spaced apartedges, said wondow means comprising in cross-sectional configuration: afirst portion substantially normal to the face plate and extendingrearwardly thereof, the first portion having a forward end and arearward end, the forward end being coincident with said first edge ofsaid window; and a second portion arcuately extending from the rearwardsurface of said face plate and from said second edge of said elongatedwindow and interconnectinG with the rearward end of said first windowportion, the arcuate second window portion being transparent and theother portions of the plate being opaque said arcuate second portionfreely passing light rays outwardly from said indicating element whilesimultaneously reflecting a substantial amount of ambient incoming lightrays into opaque portions of the plate.
 2. A light shield according toclaim 1 wherein said elongated window means in said face plate iscircular, said first edge being of a larger diameter than the diameterof said second edge, said wondow first portion forming a cylinder andsaid window second portion forming a substantially truncatedhemispheroid.
 3. A light shield according to claim 2 including an opaquecylinder selectively forming a portion of said window first portion. 4.A light shield for an indicating instrument comprising: a forward opaqueface plate in view of the user having an elongated opening for viewing acondition responsive lighted indicating element therethrough, theelongated opening having first and second edges; a window memberrearwardly of said opening in said plate, said window member comprising,in cross-sectional configuration: a first portion substantially normalto the face plate, the first portion having a forward end and a rearwardend, the forward end being coincident with said first edge of said faceplate opening, said first portion extending rearwardly of said faceplate; and a second integral arcuate portion extending from a rearwardsurface of said face plate at said second edge of said window firstportion, the first portion of the window member being light absorbingand the second portion being transparent said arcuate second portionfreely passing light rays outwardly from said indicating element whilesimultaneously reflecting a substantial amount of ambient incoming lightrays into opaque portions of the plate.
 5. A light shield according toclaim 4 wherein said elongated opening in said face plate is circular,said first edge of said opening in said face plate being of a diameterlarger than the diameter of said second edge, said window member firstportion forming a cylinder and said window member second portion forminga substantially truncated hemispheroid.
 6. A light shield according toclaim 5 including an opaque cylinder selectively forming a portion ofsaid window member first portion.